Yes, in episode 8 of season 3 NCIS, which was called "Under Covers" It wasn't a 'real' kiss however, because they were undercover as a married couple
No one. Because no once can ever replace ziva.
They already have. According to Mossad spies, Tony visited Ziva once a week during Season 3. Also, in 3x14 (maybe) The Vouyers's Web, Tony made dinner reservations for her girlfriend, but she dumped him because her husband didn't think it was a good idea. So Tony took Ziva instead :) Who knows what the future holds for these two :D
No, but Ziva is in the episode Last Man Standing
The old director got a job at homeland security, Kate was killed by Ari and Ziva is about to become an official NCIS agent, it is doubtful.
So far there only connection is being friends and fellow agents.
No. But he has been a Server/Waiter in one of the NCIS Episodes called "Under Covers" in season 3. Ziva and Tony go undercover as contract assassins and McGee gets to dress up as a hotel waiter. In that episode he events works as Zivas delivery man when he gets her special shades to her hotel room.
They are going to go into the details of Tony's family in season 7, apparently Robert Wagner is going to play Tony's dad on the 150th episode of NCIS.
The team doesn't sing a lot, but in the premiere of season 6 Ziva sings a song called "Temptation" in a Moroccan bar. Tony is a fan of music, and sings a Frank Sonatra song in one episode. Pauley Perrette, who plays Abby, is an accomplished musician and poet.
He wanted a new look so that he wouldn't get boring although I doubt that Tony's hair will ever bore anyone.
In Season 3, Episode 8, "Under Covers" they go undercover as married assassins. They do kiss, and may or may not have had sex. They did it however because they believed somebody was watching him. There were sex scenes but we do not know if they were actually having sex or faking it.
The actor who plays Kate, Sasha Alexander, is currently on a new TV Show Rizzoli and Isles, as a serious but quirky, medical examiner. Her new role is completley opposite of Kate on NCIS, but I, an avid fan of NCIS, think that her new role is better.
yes they did they kissed a lot